Dental caries formation involves a very complex series of interactions between a mixed microbial population, the host tissue and ingested substrates. Plaque pH telemetry is used to measure the acidogenic potential of various dietary components. This is not a direct measure of cariogenicity since the disease itself is not being measured. It is necessary to be able to relate acidogenicity measurements to dental caries cariogenicity. This grant proposes to measure de- and re-mineralization at the very earliest stages of dental decay simultaneously with acidogenicity measurements. This will be accomplished by placing thin tooth sections into an intra-oral appliance also containing indwelling pH electrodes. Thus the acidogenicity of a normal or specified diet may be measured along with the resultant hard tissue changes.